Methods for determining the position of mobile units such as vehicles, airplanes, and ships include time difference of arrival (TDOA), angle of arrival (AOA), ray tracing/pattern recognition, global positioning system (GPS), and hybrid methods using network connections. Among the available methods, GPS includes a plurality of satellites orbiting the earth and sending out positioning information that can be used to calculate vehicle positions. A GPS receiver receives the positioning information from the GPS satellites and uses the positioning information to obtain the position of the receiver. A more detailed discussion of a GPS receiver is found in U.S. Pat. No. 5,990,827 to Rodric C. Fan, et al. entitled “Structure of a Position Processing Apparatus,” which is incorporated herein by reference in its entirety.
In using GPS to locate mobile units, such as vehicles, each mobile unit is equipped with a GPS receiver and a wireless transmitter. Using the GPS receiver and the transmitter, the mobile unit determines its position and transmits the position to a ground station. The ground station for a conventional mobile unit locating system normally includes a map database search system and some type of storage medium that stores digital maps and travel-related information. Thus, upon receiving the mobile unit positions from the mobile units, the ground station combines the stored data with the received information and displays the present mobile unit positions on a digital map.
In some cases, a data network, such as the Internet, is involved in locating mobile units. When a data network is involved, a location determination device at or in the mobile unit determines the position of the mobile unit and transmits the position information to a network server. This data transmission from a mobile unit to the network server is accomplished wirelessly by, for example, cellular digital packet data network (CDPD) that connects to a data network (e.g., the Internet), which in turn provides access to the network server.
Pursuant to some embodiments, the mobile units may transmit raw data to the network server so that the network server can make the position determination. In a system that involves a network server, the network server instead of the ground station may access the data storage medium. The data storage medium contains location-relevant information such as maps, locations of other mobile units, locations of service stations, and locations of other destinations of interest. Thus, the data processing unit organizes the measured position and generates an area map. The area map indicates by a position marker the position of each mobile unit.
As mentioned above, location determination devices in mobile units can connect to data networks (e.g., the Internet) wirelessly through communication networks, for example a CDPD network. Additional details regarding CDPD systems are further described in K. Budka et al., “Cellular Digital Packet Data Networks,” Bell Labs Technical Journal, Vol. 2, No. 3 (Summer 1997); “Cellular Digital Packet Data Systems Specification: Releases 1.1,” CDPD Forum, Inc., Chicago (1995); and M. S. Taylor et al., “Internet Mobility: The CDPD Approach,” Prentice Hall PTR, Upper Saddle River, N.J. (1996).
In the past, however, the driver, or other occupant of a vehicle, has typically used a visual display device disposed within the vehicle to visually and manually access and interface with location-relevant information available from the data network. These conventional visual display devices provide limited visual display capability, which limits the quantity of location-relevant information and the speed at which the vehicle occupant may receive such information. Users usually enter information into the visual display device manually and receive information from the device visually, such as by reading. In some situations, or applications, such as when the user is driving, this method of interaction may be cumbersome, inefficient, or both. Due to the difficulty for the user in interfacing with information available from the data network, in the past, interaction between the user and such information has been limited.
Additionally, these conventional visual display devices are typically mounted on the vehicle. Thus, users may only access and interface with location-relevant information on the network at the vehicle and can not access or interface with the information when away from the visual display device.
A need exists, therefore, for an improved system and method for providing location-relevant information to mobile units, such as vehicles, which can provide the location-relevant information in an improved manner to overcome or alleviate limitations of conventional systems and methods.